C1 inhibiting factor

Alternative names:

C1; C1 esterase inhibiting factor

Normal values:

C1 esterase inhibitor: 16 to 33 mg/dl (160 to 330 mg/L)

Note: mg/dl = milligrams per deciliter

What abnormal results mean:

Increased complement activity may be seen in:

• cancer
• ulcerative colitis

Decreased complement activity may be seen in:

• hereditary angioedema
• bacterial infections (especially Neisseria)
• cirrhosis
• glomerulonephritis
• hepatitis
• lupus nephritis
• malnutrition
• renal transplant rejection
• systemic lupus erythematosus